1. Field of Invention
The present invention relates to rotating head magnetic tape recorders. More particularly, the invention relates to turntable type recorders where the magnetic transducer is positioned on the turntable and a length of magnetic media is positioned relatively and traversely so that the transducer reads or writes data into arcuately shaped record tracks on said media.
2. Prior Art
Longitudinally scanned rotating head recorders are well known in the prior art. Generally this type of recorder includes a plurality of recording magnetic heads which are mounted for rotation upon a disc wheel or the like. The magnetic heads are equally spaced angularly from one another about the periphery of the disc and are rotated in a common plane about a common axis. A feed mechanism is adapted to feed a length of recording media past the rotating heads in a plane parallel to the plane of rotation of the heads and in transducing relation with said heads. As a result, recording and/or reproduction is effected in a series of arcuate tracks positioned across the width of said media. A more detailed discussion of this general type of recorder is given in U.S. Pat. Nos. 3,258,269 and 2,924,668.
Although this type of prior art recorders function satisfactorily for their intended purpose, they are beset with several problems and limitations which render them unsatisfactory for use in conventional high density magnetic recording technology.
One of the problems associated with this type of device is unusual head and/or media wear which increases the frequency at which these items are replaced. The unusual head wear stems from the fact that the prior art recorders are characterized by contact recordings (i.e., the transducing head is always in contact with the media). As is well known to those skilled in the art, with contact recording the useful life of the involved components (transducers and/or media) are significantly reduced. As a result, the cost of operating these devices is relatively high.
Even in a design where the head and/or media is not always in contact, the wear problem is still present. As was discussed above, in order to transduce (i.e., read and/or write) arcuate tracks on the media the magnetic heads enter under the media at one point and exit the media at another point. The magnetic heads protrude above the surface of the positioning disc and, as such, contact or nick the media as it enters and exits the media.
Due to the unusual head wear of the prior art device, the field of use is limited. Generally, the prior art logintudinally scanned recorders are used for processing video information. As is well known to those skilled in the art, video recording is generally low density recording. With low density recording, the relative speed between the rotating heads and media is relatively low. At the relatively low speed, although the magnetic heads are in contact with the media, head and/or media wear are kept within tolerable limits. Of course, the usefull life of the heads and media (i.e. the period over which the elements may be used for recording) would be extended if the prior art devices were capable of non contact operation.
However, any attempt to extend the use of the prior art device to perform conventional high speed recording is doomed since the wear problem is intolerable. As is well known to those skilled in the art, in conventional high speed recording the relative motion between the head and media is approximately 200 inches per sec. At this speed the drag force between the media and head is relatively high should they operate in contact which would significantly augment the head and/or tape wear. As a result, the prior art devices are not suitable for conventional high speed recording.